The present invention relates to optical scanning systems and more particularly to an optical bar code scanning system which can be mounted in or on a check-out counter for scanning bar code labels on an article which is moved past a scanning aperture located in the bar code scanner.
In present-day merchandising point-of-sale operations, data pertaining to the purchase of a merchandise item is obtained by reading data encoded indicia such as a bar code printed on the merchandise item. In order to standardize the bar codes used in various point-of-sale checkout systems, the grocery industry has adopted a uniform product code (UPC) which is in the form of a bar code. Various reading systems have been constructed to read this bar code, including hand-held wands which are moved across the bar code and stationary optical reader systems normally located within the checkout counter in which the bar code is read by projecting a plurality of scanning light beams at a window constituting the scanning area of the counter over which a purchased merchandise item supporting a bar code label is moved. This scanning operation is normally part of the process of loading the item into a baggage cart. In prior scanning systems, the projected scanning beams are all focused in a single plane through which the bar code label is moved. Since many merchandise items support the bar code label at various angles and distances to the focal plane of the scanning light beams, complex and expensive optical reflecting systems have been developed to transmit these scanning beams at different angles to cover all possible orientations of the bar code label to ensure a valid scan operation. This requirement limits the operating efficiency of such scanning systems, while increasing their cost.